氧化亚铜薄膜的分子束外延生长研究

发布时间：2018-09-11 06:13

【摘要】：氧化亚铜在光伏电池、光催化、随机存储器、薄膜晶体管等领域具有广阔的应用前景。它在玻色爱因斯坦凝聚等理论研究中也起着非常重要的作用。目前的研究主要关注于其在太阳能电池中的应用,氧化亚铜的原材料储量丰富、无毒性以及低成本等优点具有很大的优势。然而现在报道的最高转换效率(6.1%)距离20%的理论极限还有很大差距。为了获得高质量、低电阻的氧化亚铜薄膜,很有必要对氧化亚铜薄膜的生长行为开展系统的研究。基于目前的研究现状,本文中使用了射频等离子体辅助分子束外延技术,选择氧化镁和硅等立方晶系衬底,制备出氧化亚铜薄膜,并采用反射式高能电子衍射仪、X射线衍射仪、高分辨透射电子显微镜、原子力显微镜、扫描电子显微镜、光致发光谱等测试方法研究了氧化亚铜薄膜的生长动力学行为及光电特性。首先我们在氧化镁(110)衬底上通过同质外延引入小面化的{100}面,然后在小面化的氧化镁(110)衬底上使用两步法外延出单一价态、单一相的氧化亚铜(113)薄膜。我们对该薄膜复杂的反射式高能电子衍射图样进行了仔细地分析,推断出薄膜的取向关系以及180°旋转畴的存在,并通过X射线衍射和高分辨透射电子显微镜的结果证实了这些结论。氧化亚铜(113)薄膜呈现连续、均匀的表面形貌,具有良好的电性,而这些特性可能是由于氧化亚铜与氧化镁界面存在大量的失配位错释放应力而抑制岛的形成所导致的。硅与氧化亚铜之间存在很大的失配,因此我们采用氧化铍作为中间层和扩散势垒,阻挡铜向硅中的扩散和反应。我们研究了不同的生长温度对氧化亚铜缓冲层的影响,发现低温会导致氧化亚铜多晶化,而高温会使氧化铍中间层发生相变从而使氧化亚铜向氧化铜转变。于是我们采取双缓冲层获得了单一取向的氧化亚铜(111)薄膜。另外,我们在硅衬底上直接沉积铜膜并低温氧化,结果并没有发现氧化亚铜的相。所有样品中都出现了硅化铜,它可能是氧化亚铜薄膜中高空穴迁移率的起源。
[Abstract]:Cuprous oxide has broad application prospects in photovoltaic cells, photocatalysis, random access memory, thin film transistors and other fields. It also plays a very important role in the theoretical study of Bose-Einstein condensation. However, the reported maximum conversion efficiency (6.1%) is far from the theoretical limit of 20%. In order to obtain high quality and low resistance cuprous oxide films, it is necessary to systematically study the growth behavior of cuprous oxide films. Cuprous oxide thin films were prepared by radio frequency plasma assisted molecular beam epitaxy on cubic substrates of magnesium oxide and silicon. Suboxide was studied by reflection high energy electron diffraction, X-ray diffraction, high resolution transmission electron microscopy, atomic force microscopy, scanning electron microscopy and photoluminescence spectroscopy. Growth kinetics and photoelectric properties of copper thin films. First, we introduce faceted {100} planes on magnesium oxide (110) substrates by homogeneous epitaxy, and then epitaxy single valence, single phase copper oxide (113) thin films on faceted magnesium oxide (110) substrates by two-step method. The diffraction patterns were carefully analyzed to deduce the orientation relationship and the existence of 180 degree rotation domains. These results were confirmed by X-ray diffraction and high-resolution transmission electron microscopy. The copper oxide (113) films exhibited continuous, uniform surface morphology and good electrical properties, which may be due to oxidation. There is a great mismatch between silicon and cuprous oxide, so we use beryllium oxide as the intermediate layer and diffusion barrier to prevent the diffusion and reaction of copper into silicon. We have studied the effect of different growth temperatures on the buffer layer of cuprous oxide. It was found that low temperature would lead to the polycrystallization of cuprous oxide, and high temperature would lead to the phase transition of beryllium oxide intermediate layer and the transition from cuprous oxide to cuprous oxide. Copper silicide appears in all the samples, which may be the origin of the high hole mobility in cuprous oxide films.
【学位授予单位】：北京邮电大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN304.21

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